Cross-referenced is U.S. patent application Ser. No. 10/237,362 filed Sep. 6, 2002 by the same inventors, and having the same assignee, entitled xe2x80x9cPrinter Lateral and Deskew Sheet Registration System.xe2x80x9d
In the exemplary and various other sheet handling devices and systems, accurate registration of the sheets is accomplished through various mechanisms and methods which require normal sheet feeding nips to open. Upon opening the sheet feeding nips, the sheet is released therefrom so that a sheet registration device is able to orient the paper. In previous designs, relatively complex and expensive solenoid driven or stepper motor driven mechanisms typically accomplished these nip openings by mechanical movement of idlers away from their drive rolls. The system and method of the disclosed embodiment eliminates such complex and expensive mechanisms associated with previous nip opening systems.
The disclosed embodiment is also an improvement over the system and method of Xerox Corp. U.S. Pat. No. 6,168,153 issued Jan. 2, 2001 to Paul N. Richards, et al, and others cited herein.
With the specific embodiment disclosed herein, a separate motor or solenoid is not required to open the upstream paper path sheet feed roller nips by moving the idlers away to allow for longer sheet deskewing and/or side registration (lateral registration) in the downstream sheet lateral registration system. The same stepper or servo motor that is used for driving the sheet feed rollers can be used. It can be simply controlled in its rotational position to selectively hold open the upstream sheet feeding nips that need to be held open for the deskewing and/or side registration of that particular sheet. Also, the mating idlers can be conventionally fixedly mounted (for further cost reductions).
This is enabled in this disclosed embodiment by larger circumference sheet feed rollers having at least two different radii (which for simplicity of description may be referred to herein as xe2x80x9cDxe2x80x9d rollers). Plural sets of these upstream xe2x80x9cDxe2x80x9d feed rollers selectively provide, with selected partial rotations, either normal sheet feeding nips or open nips allowing unobstructed variable size sheet lateral movement therein by the downstream sheet lateral registration system yet positive sheet feeding and control.
Further by way of background, various sheet lateral registration systems are known in the art, and the present system is not limited to any particular sheet deskew and/or side-shifting system. The above-cited U.S. Pat. No. 6,168,153 shows one type. The specific example schematically shown herein is one of various known TELER systems of sheet registration, which also have differential roll pair driving for sheet deskew, and in which sheet side-shifting is also provided. The sheet lateral (side-shift) registration may be accomplished in a TELER system by side-shifting the TELER sheet drive rolls and their associated components while the sheet is engaged in the feed nip of those TELER sheet drive rolls. That sheet side-shifting can provide lateral sheet registration in a known manner, as by a carriage containing the two drive rollers, and their opposing nip idlers, being axially side-shifted to side-shift a nip-engaged sheet into lateral registration. Sheet process direction registration can also be provided by the controlled common forward driving rotational velocity of the same pair of rollers.
Examples of such TELER systems include U.S. Pat. No. 5,094,442, issued Mar. 10, 1992 to Kamprath et al; U.S. Pat. Nos. 5,794,176 and 5,848,344 to Milillo et al; U.S. Pat. No. 5,219,159, issued Jun. 15, 1993 to Malachowski and Kluger (citing numerous other patents); U.S. Pat. No. 5,337,133; and other cited patents. Of interest is a Xerox Corp. U.S. Pat. No. 5,278,624, issued Jan. 11, 1994 to David R. Kamprath and Martin E. Hoover, showing another example of a TELER type of combined lateral sheet registration and deskewing system for a printer, but with only a single drive motor and reduced mass of the TELER lateral translation (side shifting) components. Reduced mass is helpful both for allowing more rapid or lower power side-shifting and the re-centering or return to a xe2x80x9chomexe2x80x9d position of TELER systems. Heretofore the latter has been done in the very short time and space available only between successive sheets in the sheet path of a high speed printer, i.e., when no sheet is in the nip of the TELER system.
Of particular background interest is a Xerox Corp. U.S. Pat. No. 5,078,384 issued Jan. 7, 1992 to Steven R. Moore. This is not a TELER system. Rather, it accomplishes sheet deskewing and downstream or forward direction registration by differential driving of two sheet drive rolls 24, 25, by two servomotors, but does not provide sheet lateral (sideways) registration by any side-shifting of those drive rolls. Thus, it does not teach or suggest (or even have the problem of) accomplishing rapid re-centering of a TELER system in between operative sheet nip engagements. However, this U.S. Pat. No. 5,078,384 does show the use of xe2x80x9cDxe2x80x9d shaped (partially relieved radius) drive rolls 24,25 to disengage those drive rolls from the sheet (opening the drive nip) when those drive rolls are rotated to the position in which the reduced radius or xe2x80x9cflatxe2x80x9d portion of those xe2x80x9cDxe2x80x9d shaped drive rolls is facing the sheet and becomes spaced therefrom due it the reduced radius of that portion of the roll.
xe2x80x9cDxe2x80x9d shaped sheet feeding rolls are, of course, used in various other paper sheet feeding applications. For example, Xerox Corp. U.S. Pat. No. 5,449,165, issued Sep. 12, 1995, discloses a 90 degree paper feed transition module with transversely mounted and intermittently rotated xe2x80x9cDxe2x80x9d shaped feed rolls. Xerox Corp. U.S. Pat. No. 4,929,128, issued May 22, 1990 to Stemmle, shows typical segmented or xe2x80x9cDxe2x80x9d shaped feed rolls for initial sheet feeding, and for duplex path sheet feeding. However, the present embodiment provides normal and even closed nip sheet nip engagement and feeding, unlike such xe2x80x9cDxe2x80x9d roller sheet feed systems in which a stationary sheet is unevenly accelerated by initial engagement of a xe2x80x9ccornerxe2x80x9d of the xe2x80x9cDxe2x80x9d roller (where the xe2x80x9cDxe2x80x9d roller transitions from it""s smaller to it""s larger radius) with the sheet.
Disclosed in the embodiment herein is an improved system for controlling, correcting and/or changing the position of sheets traveling in a sheet transport path, in particular, for rapid automatic sheet skew correction and/or side registration of a wider range of different sizes of paper or other print media sheets in or for an image reproduction apparatus, such as a high speed electronic printer, to provide deskewing and/or side registration of much longer sheets without losing positive sheet feeding control over much shorter sheets, including subsequently fed sheets in the sequence of sheets in the sheet path. This may include deskewing and/or side registration of sheets being initially fed in to be printed, sheets being recirculated for second side (duplex) printing, and/or sheets being outputted to a stacker, finisher or other output or module.
More specifically disclosed in the embodiment herein is an improved system and method for automatically engaging and disengaging an appropriate number of sequential plural spaced sheet feed-in nips of the sheet transport in the sheet path into the sheet deskewing system in accordance with a control signal corresponding to the length of the sheet to be laterally registered. The sheet xe2x80x9clengthxe2x80x9d here is the sheet dimension in the sheet feeding or sheet movement direction of the sheet path, otherwise known as the xe2x80x9cprocess direction,xe2x80x9d as such terms may be used in the art in that regard, even though, as is well known, smaller sheets are often fed xe2x80x9clong edge first,xe2x80x9d rather than lengthwise, whereas in contrast very large sheets are more often fed lengthwise. Sheet xe2x80x9cwidthxe2x80x9d as referred to herein is thus the orthogonal sheet dimension as the sheet is being fed, i.e., the sheet dimension transverse to the sheet path and the sheet movement direction.
As shown in the embodiment example, these features and improvements can be accomplished in one exemplary manner by automatically disengaging a long sheet being deskewed in a sufficient sequential number of upstream sheet feeding units to allow the deskewing of that long sheet, the number of units being disengaged depending on the length of the sheet. Yet positive nip feeding engagement of the next adjacent upstream sheet being fed can be simultaneously maintained in engaged sheet feeding units while the closely immediately preceding sheet is being deskewed, even for very short sheets.
As shown in this example, the selectable nip openings of otherwise closed sheet feeding units may be simply and reliably provided by a variable control system for the same servo or stepper drive motors driving the respective plural sheet feeding units. As further disclosed in the embodiment example, this may be provided here by controlled partial rotation of those respective drive motors, to provide reliable sheet feeding nip disengagement or engagement in each unit. The disclosed system can provide better control and reliability than trying to hold individual nips open or closed by activation, deactivation, or holding, of solenoid actuators, and does not require any additional stepper motors or servomotors.
The disclosed embodiment (or other embodiments of the generic concept) can greatly assist in automatically providing more accurate and rapid deskewing rotation and/or edge registration of a very wide range of sheet sizes, from very small sheets to very large sheets, and from thin and flimsy such sheets to heavy or stiff such sheets. This is accomplished in the disclosed embodiment by a simple, low cost, fixed position, system which does not require repositioning of any of the system components relative to the paper path, merely automatically selecting different nip openings or closings along different positions of the paper path.
The present system is well suited for cooperation and combination with an automatic deskewing and side registration system of various known types, especially those comprising a differentially driven spaced pair of sheet deskewing sheet drive rollers, for which various references are cited herein.
Examples of one such prior art type of dual differently driven nips systems for automatic deskewing and side registration of the sheets to be accurately imaged in a printer, including the appropriate controls of the differently driven sheet steering nips, and including cooperative arrayed sheet edge position detector sensors and signal generators, are already fully described and shown, for example, in Xerox Corp. U.S. Pat. Nos. 5,678,159 and 5,715,514 by Lloyd A. Williams, et al., and other patents cited therein, all of which are incorporated herein. With different nip drive velocities, the sheet can be deskewed or straightened out so that the sheet exits the steering nip pair aligned in the process direction.
The improved system disclosed herein is also desirably compatible and combinable with an elongated and substantially planer sheet feeding path upstream in the paper path from the subject deskewing and/or side registration system station, leading thereto, along which the subject sheet feeding units here are spaced. Such a long and planar sheet feeding path to the deskewing system reduces resistance to sheet rotation and/or lateral movement, especially for large, stiff, sheets. That is, a planar sheet entrance path longer than the longest sheet to be deskewed, to allow deskewing rotation of even very large and stiff sheets while those sheet are planar, rather than a path that bends sheets to cause sheet beam strength normal forces pressing against the path baffles, thus reducing any tendency for that to cause excessive resistance and/or scuffing or slippage by both the sheet feeding nips and the deskewing or steering nips.
As further disclosed in the embodiment herein, the subject improved sheet input feeding system in the upstream sheet feeding path provides for the automatic release or disengagement of a selected variable number (from 1 to 3 in the illustrated embodiment) of plural upstream sheet feeding plural nip stations or units spaced apart along the sheet path upstream of the sheet deskewing station. That selected release is automatic, and may be in response to a sheet length control signal (such as a signal from a sensor or other signal generator indicative of the approximate sheet dimension along or in the process or sheet path movement direction). The spacings and respective actuations (releases or engagements) of the selected number of plural sheet feeding nips along the upstream sheet path of that sheet path control system can provide for a wide range of sheet lengths to be positively fed, without loss of positive nip control, even short sheets, downstream to the automatic deskewing and/or side registration system. Yet once a sheet is acquired in the steering nips of the deskew system a sufficient number of said upstream sheet feeding nips can be automatically released or opened to allow for unrestrained sheet rotation and/or lateral movement by the subject system, even of very long sheets. As is well know in the art, standard sizes of larger size sheets are both longer and wider, and are often fed short-edge first or lengthwise, and thus are very long sheets in the process direction. This related cooperative automatic system also helps provide for automatic proper deskewing and/or edge registration of very small sheets, with positive feeding of even very small sheets, even with small pitch spacings and higher page per minute (PPM) rates, yet with positive feeding nip engagement of such small sheets in the same sheet input path and system as for such very large sheets.
In reference to the above, as taught, for example, in Xerox Corp. U.S. Pat. No. 4,621,801 issued Nov. 11, 1986 to Hector J. Sanchez (see especially the middle of Col. 17), it is known to release a single upstream sheet feeding nip to allow a downstream document sheet deskewing and side registration nip system to rotate (to deskew) and/or side shift the sheet. However, that only is effective for a limited range of sheet lengths. If that single releasable upstream sheet feeding nip is spaced too far away from the downstream sheet deskewing and side registration nip it cannot positively feed any sheets of lesser dimensions than that spacing. If on the other hand that single releasable upstream sheet feeding nip is spaced too far downstream it may be too far away from the next further upstream non-releasable sheet feeding nip in the sheet path. Yet if that next further upstream sheet feeding nip is positioned too far downstream it will not release the rear or trailing edge portion of long sheets in timexe2x80x94before the leading edge of that same long sheet is in the downstream sheet deskewing and side registration nip which is trying to rotate and/or side shift that sheet.
Another disclosed feature and advantage illustrated in the disclosed embodiments is that the plural positive sheet feeding units can all share a high number and percentage of identical or almost identical components, thus providing significant design, manufacturing, and servicing cost advantages.
The above and other features and advantages allow for accurate registration for imaging of a wider variety of image substrate sheet sizes. In reproduction apparatus in general, such as xerographic and other copiers and printers or multifunction machines, it is increasingly important to be able to provide faster yet safer and more reliable, more accurate, and more automatic, handling of a wide variety of the physical image bearing sheets, typically paper (or even plastic transparencies) of various sizes, weights, surfaces, humidity, and other conditions. Elimination of sheet skewing or other sheet misregistration is very important for proper imaging. Otherwise, borders and/or edge shadow images may appear on the copy sheet; and/or information near an edge of the image may be lost. Sheet misregistration or misfeeding can also adversely affect further sheet feeding, ejection, and/or stacking and finishing.
Further by way of background, various types of variable or active, as opposed to passive, sheet side shifting or lateral registration systems are known in the art. It is particularly desirable to be able do so xe2x80x9con the fly,xe2x80x9d without stopping the sheets, while the sheet is moving through or out of the reproduction system at a normal process (sheet transport) speed. In addition to the two sheet side registration systems patents cited above providing combined sheet deskewing, the following patent disclosures, and other patents cited therein are noted by way of some other examples of active sheet lateral registration systems with various means for side-shifting or laterally repositioning the sheet: Xerox Corp. U.S. Pat. No. 5,794,176 issued Aug. 11, 1998 to W. Milillo; U.S. Pat. No. 4,971,304 issued Nov. 20, 1990 to R. Lofthus; U.S. Pat. No. 5,156,391 issued Oct. 20, 1992 to G. Roller; U.S. Pat. No. 5,078,384 issued Jan. 7, 1992 to S. Moore; U.S. Pat. No. 5,094,442 issued Mar. 10, 1992 to D. Kamprath, et al; U.S. Pat. No. 5,219,159 issued Jun. 15, 1993 to M. Malachowski, et al; U.S. Pat. No. 5,169,140 issued Dec. 8, 1992 to S. Wenthe; and U.S. Pat. No. 5,697,608 issued Dec. 16, 1997 to V. Castelli, et al. Also, IBM U.S. Pat. No. 4,511,242 issued Apr. 16, 1985 to Ashbee, et al.
The present sheet handling system can also be used with many of these other deskewing systems.
Note that in some reproduction situations, it may even be desired to deliberately provide a substantial, but controlled, sheet side-shift, varying with the sheet""s lateral dimension, even for sheets that do not enter the system skewed, such as in feeding sheets from a reproduction apparatus with a side registration system into a connecting finisher having a center registration system. Or, in duplex printing, for providing appropriate or desired side edge margins on the inverted sheets being recirculated for their second side printing after their first side printing. The present system can also be utilized in combination with those other sheet side-shifting systems, which may be generally encompassed by the term xe2x80x9csheet deskewing systemxe2x80x9d or xe2x80x9cskew correction systemxe2x80x9d as used in the claims herein.
Merely as examples of the variety and range of even standard sheet sizes used in printing and other reproduction systems, in addition to well-known standard sizes with common names such as xe2x80x9cletterxe2x80x9d size, xe2x80x9clegalxe2x80x9d size, xe2x80x9cfoolscap,xe2x80x9d xe2x80x9cledgerxe2x80x9d size, A-4, B-4, etc., there are very large standard sheets of uncut plural such standard sizes, such as 14.33 inch (36.4 cm) wide sheets, which are 20.5 inches (52 cm) long, or even larger sheets. Such very large sheets may be used, for example, for single image engineering drawings, or printed xe2x80x9c4-upxe2x80x9d with 4 letter size images printed thereon per side, and then sheared or cut into four letter size sheets, thus quadrupling the effective PPM printing or throughput rate of the reproduction apparatus, and/or folded into booklet, Z-fold, or map pages. The disclosed system can provide a printer with accurate sheet to image registration by effectively handling even such very long sheets, although that is not mandatory or a claim limitation. Yet the same system here can also effectively handle very much smaller sheets such as 5.5 inch (14 cm) by 7 inch (17.8 cm) or 7 inch (17.8 cm) by 10 inch (25.4 cm) sheets. Some other common standard sheet sizes are listed and described in the table below.
A specific feature of the specific embodiments disclosed herein is to provide a printing system having a sheet transport system for moving print media sheets in a process direction from upstream to downstream in a sheet transport path, and a sheet lateral registration system in said sheet transport path downstream of said sheet transport system providing for movement of said sheets laterally of said process direction, wherein said print media sheets have a wide range of different sheet dimensions in said process direction to be accommodated by said sheet lateral registration system, wherein said sheet transport system comprises a plurality of sheet transport units having sheet feeding nips, said sheet transport units being spaced from one another and from said sheet lateral registration system from upstream to downstream along said sheet transport path, each of said sheet transport units having sheet feed rollers providing said sheet feeding nips and a drive system for rotationally driving said sheet feed rollers, said sheet feeding nips of said plurality of sheet transport units being engageable with a sheet being fed in said process direction in said sheet transport path for positively feeding said sheet downstream in said sheet transport path from one said sheet transport unit to another said sheet transport unit and from a downstream one of said sheet transport units to said sheet lateral registration system, each of said plurality of sheet transport units being selectably independently operable by rotation of said sheet feed rollers by said drive system thereof to release said sheet by opening said sheet feeding nips thereof and to positively engage said sheet for feeding said sheet downstream by closing said sheet feeding nips thereof; a sheet length signaling system providing a sheet length control signal proportional to said variable dimension of said sheet in said sheet transport path, a control system for automatically so operating a selected plurality of said sheet transport units by opening said sheet feeding nips thereof in response to said sheet length control signal when said sheet is in said sheet lateral registration system, said sheet feed rollers of said plural sheet transport units having at least two different circumferential lengths of at least two different roller radii, comprising first and larger circumferential lengths with larger radii and second and smaller circumferential lengths with smaller radii, said control system providing selective rotations of said sheet feed rollers of selected said sheet transport units to selectively provide, by selected partial rotations of said sheet feed rollers, a first operating mode of closed sheet feeding nips with said first and larger circumferential lengths with larger radii, and a second operating mode with said second and smaller circumferential lengths with smaller radii to provide open nips for said selected sheet transport units providing unobstructed sheet lateral movement therein by said sheet lateral registration system.
Further specific features disclosed herein, individually or in combination, include those wherein there are at least three said selectably actuated sheet transport units spaced along said sheet transport path upstream of said sheet lateral registration system; and/or wherein said first and larger circumferential lengths with larger radii of said sheet feed rollers of said plural sheet transport units are circumferential lengths which are equal to or greater than said spacing of said plural sheet transport units along said sheet transport path upstream of said sheet lateral registration system; and/or a sheet feeding and registration system for positive feeding print media sheets in a process direction from upstream to downstream in a sheet transport path containing a sheet lateral registration system providing selective movement of said same sheets laterally of said process direction, wherein said print media sheets have a wide range of different sheet dimensions in said process direction to be accommodated by said sheet lateral registration system, comprising a plurality of sets of rotatably driven sheet feed rollers defining sheet feeding nips are spaced from one another along said sheet transport path to provide said sheet feeding, said sheet feed rollers of said plural sets thereof having at least two different circumferential lengths of at least two different roller radii, comprising first and larger circumferential lengths with larger radii and second and smaller circumferential lengths with smaller radii, a sensing system for sensing the length of a sheet to be laterally registered by said sheet lateral registration system, a rotational drive system for selective rotations of said sheet feed rollers of selected said sets thereof in response to said sensing of the length of a sheet to be laterally registered to provide, in selected partial rotations of selected said sets of said sheet feed rollers, a first operating mode of closed sheet feeding nips with said first and larger circumferential lengths with larger radii for said sheet feeding, and a second operating mode with said second and smaller circumferential lengths with smaller radii to provide open nips for unobstructed sheet lateral movement therein by said sheet lateral registration system; and/or a sheet feeding and registration method for positive feeding print media sheets in a process direction from upstream to downstream in a sheet transport path integrated with sheet lateral registration by selective movement of said same sheets laterally of said process direction, wherein said print media sheets have a wide range of different sheet dimensions in said process direction to be accommodated by said sheet lateral registration, wherein said sheet feeding is provided by a plurality of sets of rotatably driven sheet feed rollers defining sheet feeding nips spaced from one another along said sheet transport path, said sheet feed rollers of said plural sets of rotatably driven sheet feed rollers having at least two different circumferential lengths of at least two different roller radii, comprising first and larger circumferential lengths with larger radii and second and smaller circumferential lengths with smaller radii, sensing the length of a sheet to be provided with said sheet lateral registration, providing selective rotations of said sheet feed rollers of selected said sets thereof in response to said sensing of the length of a sheet to provide in selected partial rotations of said sheet feed rollers a first operating mode of closed sheet feeding nips with said first and larger circumferential lengths with larger radii for said sheet feeding, and a second operating mode with said second and smaller circumferential lengths with smaller radii providing open nips for unobstructed sheet lateral movement therein by said sheet lateral registration system; and/or wherein said selective rotations of said sheet feed rollers are by a single motor for each said set thereof which provides both said sheet feeding and said selective open and closed nips thereof.
As is taught by the above-cited and other references, the disclosed system may be operated and controlled as described herein by appropriate operation of known or conventional control systems. It is well known and preferable to program and execute printing, paper handling, and other control functions and logic with software instructions for conventional or general purpose microprocessors, as taught by numerous prior patents and commercial products. Such programming or software may of course vary depending on the particular functions, software type, and microprocessor or other computer system utilized, but will be available to, or readily programmable without undue experimentation from, functional descriptions, such as those provided herein, and/or prior knowledge of functions which are conventional, together with general knowledge in the software and computer arts. Alternatively, the disclosed control system or method may be implemented partially or fully in hardware, using standard logic circuits or VLSI designs.
It is well known in the art that the control of sheet handling systems may be accomplished by conventionally actuating them with signals from a microprocessor controller directly or indirectly in response to programmed commands and/or from selected actuation or non-actuation of conventional switch inputs or sensors. The resultant controller signals may conventionally actuate various conventional electrical servo or stepper motors, clutches, or other components, in programmed steps or sequences.
In the claims herein the term xe2x80x9csheet,xe2x80x9d xe2x80x9ccopy,xe2x80x9d or xe2x80x9ccopy sheetxe2x80x9d refers to a usually flimsy physical sheet of paper, plastic, or other suitable physical substrate for images, whether precut or initially web fed and cut. Likewise the terms lateral registration or sheet side shifting as used in the claims herein encompasses sheet deskewing, or sheet lateral side-shifting without deskewing, or both, unless otherwise specifically indicated. The terms xe2x80x9cprinter,xe2x80x9d xe2x80x9cprinting system,xe2x80x9d or xe2x80x9creproduction systemxe2x80x9d as used herein encompass any type of printer, copier or multi-functional device which may utilize the claimed features.
As to specific components of the subject apparatus, or alternatives therefor, it will be appreciated that, as is normally the case, some such components are known per se in other apparatus or applications which may be additionally or alternatively used herein, including those from art cited herein. All references cited in this specification, and their references, are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features, and/or technical background. What is well known to those skilled in the art need not be described here.